Avrim Blum, Prasad Chalasani, Santosh Vempala. A constant-factor approximation for the ::::k::::-MST problem in the plane. In Proceedings of the Twenty-Seventh Annual ACM Symposium on Theory of Computing, 29 May-1 June 1995, Las Vegas, Nevada, USA. pages 294-302, ACM, 1995. [doi]
Abstract is missing.